Traffic film remover. Get the proper stuff though not the rubbish halfords sell.
Treat the side walls with meguiars endro tyre shine afterwards to stop them drying out and the jobs a good un
Try your local autosmart dealer or I use a valleting supplier in bridport for mine.
My magic looked worse than those and cleaned up. The logos may wash off though
I did this with mine I only rode it for around 100 metres so its not the best of tests but it was wet. I had no probs at all, i didnt notice any excess rolling or lack of traction.